Digital radiographic volume imaging provides three-dimensional (3-D) images that have been reconstructed from a series of 2-D images taken over a succession of angles of the x-ray source relative to the detector. Acquisition of the 2-D projection images used for cone beam CT employs a large-area digital detector, such as a digital radiography (DR) detector that is typically used for conventional single projection radiography.
One factor that affects the quality of volume reconstruction relates to the number of 2-D projection images acquired. Projection images are generally obtained at evenly spaced angular increments; having images at a sufficient number of angles helps to provide enough data to minimize or eliminate aliasing effects such as view aliasing artifacts, typically appearing in the form of regularly spaced streaks, and other image processing problems.
Each projection image, however, requires exposure of the patient. Thus, although having more 2-D projection image data is advantageous for 3-D image reconstruction, it would be preferable to reduce the number of 2-D projection images that are obtained, thereby reducing exposure risks to the patient. In addition, it would be beneficial to reduce the required scan time in order to help reduce image reconstruction problems due to patient motion.
Thus, there would be advantages to volume imaging methods that can obtain sufficient projection image content for accurate volume reconstruction while reducing dosage requirements.